it is easier to delete / ignore the email than type "remove" besides if you respond to these spams it shows them that you noticed them and encourage more.

On the other hand, I found that in some cases you nicely ask to be removed and they ignore your request. This does get the blood boiling so I usually repsond back with 2 large attachments and if this doesn't get their attention keeping adding more and more attachments until you crash their mail server.